That's because he's totally pissed off by what's happened. If you saw the little clues in the cinematic, the fight took place in Metropolis where no one has survived, meaning Lois Lane died also. And during the cinematic Diana (Wonder Woman) died also. So that being said, Metropolis gone, Lois Lane and Diana, dead. Superman has lost everything and is in a furious state of rage where he goes to extreme length to even kill the villains such as Black Adam and saying to Lex Luthor that he doesn't deserve to live.